N,n&#39;-thio-bis-carbamic acid amides

ABSTRACT

N,N&#39;&#39;-THIO-BIS-CARBAMIC ACID AMIDES, THEIR PREPARATION BY REACTING AT LEAST 2 MOLS OF A CARBOXYLIC ACID AMIDE WITH 1 MOL OF SULPHUR DICHLORIDE IN THE PRESENCE OF AN ACID BINDING AGENT AND THEIR UTILITY AS RUBBER VULCANIZATION RETARDERS.

nited States Patent 3,770,826 N,N-THIO-BlS-CARBAMIC ACID AMIDES RiidigerSchubart and Ernst Roos, Cologne, and Manfred Abele, Porz, Germany,assignors to Bayer Aktiengesellschaft, Leverkusen, Germany No Drawing.Original applicah'on Nov. 18, 1970, Ser. No. 90,859, now Patent No.3,671,503. Divided and this application Dec. 10, 1971, Ser. No. 206,869

Int. Cl. C07c 103/30 US. Cl. 260-558 S 4 Claims ABSTRACT OF THEDISCLOSURE N,N'-thio-bis-carbamic acid amides, their preparation byreacting at least 2 mols of a carboxylic acid amide with 1 mol ofsulphur dichloride in the presence of an acid binding agent and theirutility as rubber vulcanization retarders.

CROSS REFERENCE TO RELATED APPLICATION This application is a divisionalapplication of Ser. No. 90,859 filed Nov. 18, 1970, and now US. Pat.3,671,503.

The present invention relates to the use of N,N'-thiobis-carboxylic acidamides as vulcanisation retarders in the production and processing ofmixtures based on natural or synthetic rubber. The invention alsorelates to new N,N-thio-bis-carboxylic acid amides and theirpreparation.

In the production and processing of rubber mixtures which containvulcanising agents, e.g. sulphur and accelerators, a certain amount ofpremature vulcanisation, known as scorching, may occur before thepro-per vulcanisation (see Bayer-Mitteilungen fiir die Gummi-Industrie,No. 42 of Jan. 5, 1968, pp. 3-7, in particular page 3, lefthand column).This scorching may occur, for example, in the mixer or during any of thesubsequent processes such as extruding or calendering.

It is known that the risk of scorching can be reduced by the addition ofa N-nitrosoamine, especially N-nitrosodiphenylamine, to the rubbermixture (see Technical Information R 22 Rubber Chemicals of ImperialChemical Industries, Manchester, England, pp. 1-11, in particular page1; Rubber Chemistry and Technology, vol. 30 (1957), pp. 1291-1346, inparticular page 1302, lines 3 and 4; Rubber Journal, March 1967, p. 11,right-hand column, paragraph 2, in particular line 18 of the righthandcolumn).

In certain circumstances, however, the use of these retarders leads tothe formation of porous vulcanisates due to the nitroso group beingsplit off (see Technical Information R 22 Rubber Chemicals of ImperialChemical Industries, Manchester, England, pp. 1-11, in particular page2, second paragraph). Furthermore, these compounds not only influencethe scorching but also have a marked efiect on the entire vulcanisationprocess, i.e. the vulcanisation time is increased (see BayerMitteilungen fiir die Gummi-Industrie, No. 42 of Jan. 5, 1968, pp. 3-7,in particular page 3, right-hand column, lines 39- 45, and page 3,right-hand column, last paragraph, in particular lines 47, 48, 55 and56).

Furthermore, a rather large dose of an N-nitrosoamine is required forachieving a given retardingeffect.

Patented Nov. 6, 1973 It has now been found thatN,N'-thio-bis-carboxylic acid amides of the general formula:

in which R and R independently of each other represent hydrogen or analkyl radical, a cyclo-alkyl radical, an aryl radical optionallysubstituted by one or more alkyl groups, or an aralkyl radical, andtogether may form a carbocyclic ring having up to 12 carbon atoms,

are suitable for use as vulcanisation retarders in the known methods ofproducing and processing mixtures which contain natural or syntheticrubber.

The N,N-thio-bis-carboxylic acid amides surprisingly show asubstantially more powerful effect as vulcanisation retarders than theN-nitrosoamines known in the art. Moreover, they do not give rise toporous vulcanisates and, when used in suitable quantities, they haveless influence on the time required for complete vulcanisation than haveN-nitrosoamines.

The following are examples of radicals R and R in the Formula I:unbranched or branched alkyl groups having from 1 to 6 carbon atoms,such as methyl, ethyl, npropyl, isopropyl, n-butyl, secondary butyl,isobutyl, tertiary butyl, n-pentyl, isoamyl, n-hexyl; thecyclohexylmethyl radical; cycloalkyl groups such as cyclopentyl,cyclohexyl or methylcyclohexyl; aralkyl groups such as benzy,phenylethyl, phenylpropyl or phenylisopropyl. The following arementioned as examples of aryl radicals R and R which may be substitutedby alkyl groups: phenyl, u-naphthyl, methylphenyl, ethylphenyl,n-propylphenyl, isopropylphenyl, n-butylphenyl or tertiary butylphenyl,any of the previously mentioned alkyl groups being either in the ortho-,metaor para-position of the phenyl radical; also,

2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl,

2, fi-dimethylphenyl, 3,5-dimethylphenyl, 3,4-dimethylphenyl,2,3-diethylphenyl, 2,4-diethylphenyl, 2,5-diethylphenyl,2,6-diethylphenyl, 3,4-diethylphenyl, 3,5-diethylphenyl,2-methyl-3-ethylphenyl, 2-methyl-4-ethylphenyl, 2-methyl-5-ethylphenyl,2-methyl-6-ethylphenyl, 3-methyl-2-ethylphenyl, 3-methyl-4-ethylphenyl,3-methyl-5-ethylphenyl, 4-methyl-2-ethylphenyl, 4-methyl-3-ethylphenyl,S-methyl-Z-ethylphenyl,

2,3,4-trimethylphenyl, 3,4,6-trimethylphenyl, 3,4,5-trimethylphenyl,2,3-dimethyl-4-ethylphenyl, 2,3-dimethyl--ethylphenyl,2,3-dimethyl-6-ethylphenyl, 2,4-dimethyl-3-ethylphenyl,2,4-dimethyl-5-ethylphenvl, 2,4-dimethyl-6-ethylphenyl, 2,5-dimethyl-3-ethylphenyl, 2,5-dimethyl-4-ethylphenyl,2,5-dimethyl-6-ethylphenyl, 2,6-dimethyl-3-ethylphenyl,2,6-dimethyl-4-ethylphenyl, 3,4-dimethyl-2-ethylphenyl, 3,4-dimethyl-S-ethylphenyl, 3,4-dimethyl-6-ethylphenyl, 3 ,5-dimethyl-4-ethylphenyl, 3,5-dimethyl-6-ethylphenyl,4-methyl-2,3-diethylphenyl, S-methyl-Z,3-diethylphenyl,fi-methyl-2,3-diethylphenyl, 3-methyl-2,4-diethylphenyl,5-methyl-2,4-diethylphenyl, 6-methyl-2,4-diethylphenyl,3-methyl-2,5-diethylphenyl, 4-methyl-2,5-diethylphenyl,6-methyl-2,5-diethylphenyl, 3-methyl-2,6-diethylphenyl,4-methyl-2,6-diethylphenyl, 2-methyl-3 ,4-diethylphenyl,5-methyl-3,4-diethylphenyl, 6-methyl-3,4-diethylphenyl,4-methyl-3,5-diethylphenyl, 6-methyl-3,S-diethylphenyl,2,3,4-triethylphenyl, 2,3,5-triethylphenyl,

2, 3,6-triethylphenyl, 2,4,5-triethylphenyl, 2,4,6-triethylphenyl and3,4,5-triethylphenyl.

The following are mentioned as specific examples of compounds which maybe used for the invention:

N,N'-thio-bis-formamide, N,N'-thio-bis-acetamide,N,N'-thio-bis-propionamide,

N,N-thio-bis- N-methylformamide N,N'-thio-bis-(N-methyl acetamide),N,N'-thio-bis-(n-ethyl acetamide), N,N'-thio-bis-(N-propyl acetamide),N,N'-thio-bis-(N-methy1 propionamide), N,N-thio-bis- (N-ethylpropionamide N,N'-thio-bis- (N-methyl butyric acid amide),N,N-thio-bis-(N-ethyl butyric acid amide), N,N-thio-bis-(N-methyliso'butyric acid amide), N,N-thio-bis-(N-ethyl isobutyric acid amide),N,N'-thio-bis-(N-methyl pentane carboxylic acid amide), N,N-thio-bis-(N-cyclohexyl methyl acetamide), N,N'-thio-bis-(N-cyclopentylacetamide), N,N-thio-bis- (N-cyclohexyl acetamideN,N'-thio-bis-(N-methyl cyclohexyl acetamide), N,N'-thio-bis-(benzylacetamide),

N,N-thio-bis- (N-benzyl formarnide) N,N'-thio-bis- (N-phenylethylacetamide), N,N-thio-bis- (N-phenyl formamide) N,N-thio-bis-(N-phenylacetamide), N,N-thio-bis-(N-a-naphthyl acetamide), N,N-thio-bis-N-4-methylphenyl acetamide) N,N'-thio-bis(N-4-ethylphenyl acetamide),N,N-thio-bis-(N-Z-methylphenyl acetamide),N,N'-thio-bis-(N-Z-ethylphenyl acetamide),N,N-thio-bis-(N-2,3-dimethylphenyl acetamide), N,N'-thio-bis-(N-2,4-dimethylphenyl acetamide N,N'-thio-bis-(N-2,6-dimethylphenylacetamide),

4 N,N-thio-bis-(N-2,5-diethylphenyl acetamide),N,N-thio-bis-(N-3,4-diethylphenyl acetamide),N,N-thio-bis-(N-2-methyl-4-ethylphenyl acetamide), N,N'-thio-bis-(N-4-methyl-3-ethylphenyl acetamide)N,N-thio-bis-(N-2,3,4-trimethylphenyl acetamide),N,N-thio-bis-(N-2,4,6-trimethylphenyl acetamide), N,N'-thio-bis(N-phenylpropionamide) N,N-thio-bis-(N-Z-methylphenyl propionamide),N,N'-thio-bis- (N-benzyl propionamide) N,N-thio-bis-(N-phenyl butyricacid amide), N,N-thio-bis-benzamide,

N,N-thio-bis(N-methyl benzarnide), N,N'-thio-bis- (N-ethyl benzamideN,N'-thio-bis-(N-propyl benzamide), N,N-thio-bis-(N-cyclohexylbenZa-mide), N,N'-thiobis- (N-cyclopentyl benzamide) N,N'-thio-bis-(N-methylcyclohexyl benzamide) N,N'-thio-bis-(N-phenylcyclohexanecarboxylic acid amide), N,N'-thio-bis(N-4-methylphenylcyclohexanecarboxylic acid amide), N,N'-thio-bis- (N-phenyl benzamide),N,N'-thio-bis-(N-4-methylphenyl benzamide), N,N'-thio-bis-(N-Z-methylphenyl benzamide) N,N'-thio-bis- (N-3-methylphenyl benzamine)N,N-thio-bis-(N-phenyl-4-methyl benzamide),N,N-thio-bis-(N-Z-methylphenylmethyl benzamide),N,N-thio-bis-(N-phenyl-2,4,6-trirnethyl benzamide),N,N-thio-bis(N-methyl-2,4,6-trimethylbenzamide),N,N'thio-bis-(N-2-methylphenyl-2,4,6trimethy1 benzamide),N,Nthio-bis-(N2,6-dimethylphenyl benzamide), N,N-thio-bis-N-2,4,6-trimethylphenyl benzamide) N,N'-thio-bis- N-u-naphthyl benzamideN,N'-thio-bis-(N-fl-naphthyl benzamide),N,N'-thio-bis-(N-phenyl-a-naphthalene carboxylic acid amide),N,N'-thio-bis-(N-a-naphthyl-m-naphthalene carboxylic acid amide),N,N-thio-bis-(N-phenyl-a-naphthalene carboxylic acid amide) andN,N-thio-bis-(N-phenyl-e-naphthalene carboxylic acid amide).

The following are examples of compounds of Formula I where R and R forma carbocyclic ring: N,N'-thio-bispyrrolidine-Z;N,N'-thio-bis-caprolactarn; N,N'-thi0-bispiperidone-Z andN,N'-thio-bis-dodecanelactam.

Suitable rubbers for the production and processing of mixtures based onnatural or synthetic rubber are, for example, natural rubber orsynthetic rubber-like polymers which are obtained e.g., from conjugateddiolefins such as butadiene, dimethylbutadiene, isoprene and itshomologues, or copolymers of such conjugated diolefins withpolymerisable vinyl compounds such as styrene, amethyl styrene,acrylonitrile, methacrylonitrile, acrylates or methacrylates.

The retarders used according to the invention may be mixed with therubber in the conventional manner, for example using mixing rollers oran internal mixer. They are preferably added before or together with theother constituents but they may also be added last. The amount ofretarder according to the invention should preferably be from 0.05 to5.0% by weight, and preferably from 0.1 to 1.5% by weight, based on therubber.

The rubber mixtures to be treated contain, of course, the conventionaladditives required for vulcanisation, such as vulcanising agents andaccelerators. The vulcanising agent, e.g. sulphur, may be used in theconventional quantity for vulcanisation, generally 0.2 to 5.0% by weightof the rubber. Examples of suitable accelerators are thiazoles such as2-mercaptobenzothiazole or benzothiazyl sulphenomorpholide, guanidinessuch as diphenyl guanidine or di-o-tolyl-guanidine, dithiocarbamatessuch as diethyldithiocarbamic acid zinc, and thiurams such astetramethyl thiuramic disulphide or tetramethyl thiuramic monosulphide.Mixtures of accelerators may also be used. The accelerator is generallyused in a quantity of from 0.05 to by weight, preferably 0.05 to 2.5% byweight, and in particular 0.1 to 1.5% by weight, based on the rubber.

The rubber mixture may also contain other known auxiliary substances,e.g. active or inactive fillers such as chalk or carbon black,antioxidants, antiozonants, waxes, pigments, zinc oxides, fatty acidssuch as stearic acid or processing oils.

Vulcanisation of the rubber may be carried out by heating the rubber tothe usual temperatures, preferably to a temperature of from 120 C. to170 C., although higher or lower temperatures may also be employed.

The invention also relates to new N,N'-thio-bis-carboxylic acid amidesof the formula:

in which R' and R represent, independently of each other, hydrogen or analkyl radical, a cycloalkyl radical, an aryl radical which may besubstituted by one or more alkyl groups, or an aralkyl radical.

The following are examples of the radicals R and R straight chained orbranched alkyl groups having 1 to 6 carbon atoms, such as methyl, ethyl,n-propyl, isopropyl, n-butyl, secondary butyl, isobutyl, tertiary butyl,n-pentyl, isoamyl, n-hexyl; the cyclohexylmethyl radical; cycloalkylgroups such as the cyclopentyl, cyclohexyl or methylcyclohexyl groups;aralkyl groups such as benzyl, phenylethyl, phenylpropyl orphenylisopropyl. The following are examples of suitable aryl radicals Rand R optionally substituted by one or more alkyl groups: phenyl,u-naphthyl, methylphenyl, ethylphenyl, n-propylphenyl. isopropylphenyl,n-butylphenyl and tertiary butylphenyl, all these alkyl groups beingeither in the ortho, metaor para-position of the phenyl radical;furthermore:

2,3-din1ethylphenyl, 2,4-dimethylphenyl,

2,5 -dimethylphenyl, 2,6-dimethylphenyl, 3,5-dimethylphenyl,3,4-dimethylphenyl, 2,3-diethylphenyl, 2,4-diethylphenyl,2,5-diethylphenyl, 2,6-diethylphenyl, 3,4-diethylphenyl,

3,5 -diethylphenyl, 2-methy1-3-ethylphenyl, 2-methyl-4-ethylphenyl,2-methyl-5-ethylphenyl, 2-methyl-6-ethylphenyl, 3-methyl-2-ethylphenyl,3-methyl-4-ethylphenyl, 3-methyl-5-ethylphenyl, 4-methyl-2-ethylpheny],4-methyl-3-ethylphenyl, S-methyI-Z-ethylphenyl, 2,3,4-trimethylphenyl,

3,4, 6-trimethylphenyl, 3,4,5-trimethylphenyl,2,3-dimethyl-4-ethylphenyl, 2,3-dimethyl-5-ethylphenyl,2,3-dimethyl-6-ethylphenyl, 2,4dimethyl-3-ethylphenyl,2,4-dimethyl-S-ethylphenyl, 2,4-dimethyl-6-ethylphenyl, 2,5-dimethyl-3-ethylphenyl,

2,5 -dimethyl-4-ethylphenyl, 2,5-dimethyl-6-ethylphenyl,2,6-dimethyl-3-ethylphenyl, 2,6-dimethyl-4-ethylphenyl,3,4-dimethyl-2-ethylphenyl, 3,4-dimethyl-S-ethylphenyl,3,4-dimethyl-6-ethylphenyl, 3,5 -dimethyl-4-ethy1pheny1, 3 ,5-dimethyl6-ethylphenyl, 4-methyl-2,3-diethylphenyl,5-methyl-2,3-diethylphenyl, 6-methyl-2,3-diethylphenyl,3-methyl-2,4-diethylphenyl, 5-methyl-2,4-diethylphenyl,6-methyl-2,4-diethylphenyl, 3-methyl-2,S-diethylphenyl,4-methyl-2,5-diethylphenyl, 6-methyl-2,5-diethylphenyl,3-methyl-2,6-diethylphenyl, 4-methyl-2,6-diethylphenyl,Z-methyl-3,4diethylphenyl, 5-methyl-3,4-diethylpher1yl,6-methyl-3,4-diethylphenyl, 4-methyl-3,S-diethylphenyl,6-methyl-3,S-diethylphcnyl, 2,3,4-triethylphenyl, 2,3,5-triethylphenyl,2,3,6-triethylphenyl, 2,4,5-triethylphenyl, 2,4,6-triethylphenyl and3,4,5-triethylphenyl.

The following are specific examples of new compounds of the Formula II:

N,N'-thio-bis-formamide,

N,N'-thio-bis-acetarnide, N,Nthio-bispropionamide,

N,-N'-thio-bis- (N-methyl formamide N,N-thio-bis-(N-methyl acetamide),N,N-thio-bis- (N-ethyl acetamide N,N'-thio-bis- (N-propyl acetamideN,N'-thio-bis-(N-methyl propionamide), N,N-thio-bis-(N-ethylpropionamide), N,N'-thio-bis-(N-methyl butyric acid amide),N,N'-thio-bis-(N-ethyl butyric acid amide), N,N'-thio-bis-(N-methylisobutyric acid amide), N,N'-thio-bis-(N-ethyl isobutyric acid amide),N,N-t hio-bis-(N-methyl pentane carboxylic acid amide),N,N'-thi0-bis-(N-cyclohexylmethyl acetamide),N,N'-thio-bis-(N-cyclopentyl acetamide), N,N'-thio-bis- (N-cyclohexylacetamide) N,N'-thio-bis- (N-methylcyclohexyl acetamideN,N'-thio-bisbenzyl acetamide N,N-thio-bis- (N-benzyl formamide)N,N-thio-bis- (N-phenylethylacetamide) N,N'-thio-bis-(N-phenylformamide), N,'N'-thio-bis-(N-phenyl acetamide), N,N-thio-bis-N-a-naphthyl acetamide) N,N-thio-bis-(N-4-methylphenyl acetamide)N,N'-thio-bis- (N-4-cthylphenyl acetamide) N,N'thio-bis-(N-2-ethylpheny1acetamide), N,N'-thio-bis- (N-2,3-dimethylphenyl acetamide N,N-thio-bis-N-2,4-dimethylphenyl acetamide N,N'-thio-bis-(N-2,6-dimethylphenylacetamide), N,N'-thio-bis-(N-2,5-diethylphenyl acetamide),N,N'-thio-bis-(N-3,4-diethylphenyl acetamide),N,N'-thio-bis-(N-2-methyl-4-ethylphenyl acetamide),N,N'-thio-bis-(N-4-methyl-3-ethylphenyl acetamide),N,N'-thio-bis-(N-2,3,4-trimethylphenyl acetamide),N,N-thio-bis(N-2,4,6-trimethylphenyl acetamide), N,N-thio-bis-(N-phenylpropionamide), N,N'-thio-bis-(N-Z-methylphenyl propionamide),N,N-thio-bis- (N-benzyl propionamide) N,N-thio-bis-(N-butyric acidamide), N,N'-thio-bis-benzamide,

7 N,N-thio-bis- (N-methyl benzamide) N,Nthio-bis- N-ethyl benzamideN,N'-thio-bis- (N-propyl benzamide N,N'-thio- (N-cyclohexyl benzamideN,N'-thiobis- N-cyclopentyl benzamide) N,N'-thio-bis-(N-methylcyclohexylbenzamide), N,N'-thio-bis- (N-phenylcyclohexane carboxylic acid amide),N,N-thio-bis-(N-4-methylphenyl-cyclohexane carboxylic acid amide),N,N'-thio-bis- (N-phenyl benzamide N,N'-thio-bis- N-4-methylphenylbenzamide) N,N'-thio-bis-(N-Z-methylphenyl benzamide) N,N -thio-bis-(N-3-methylphenyl benzamide N,N'-thio-bis- N-phenyl-4-methyl benzamideN,N-thio-bis-(N-2-methylphenylmethyl benzamide), N,N'-thi0-bis-(N-phenyl-2,4,6-trimethylbenzamide) N,N'-thio-bis-(N-methyl-2,4,6-trimethyl benzamide N,N-thio-bis-(N-Z-methylphenyl-2,4,6-trimethyl benzamide), N,N'-thio-bis-(N-2,6-dimethylphenyl benzamide) N,N-thio-bis- (N-2,4,6-trimethylphenylbenzamide N,N-thio-bis-(N-a-n aphthyl benzamide N,N-thio-bis-(N-B-naphthyl benzamide N,N-thio-bis- (N-phenyl-a-naphthalene carboxylicacid amide), N,N-thio-bis-(N-phenyl-B-naphthalene carboxylic acidamide), and N,N'-thio-bis-(N-a-naphthyl-a-naphthalene carboxylic acidamide). The new compounds of the Formula II are prepared by reacting atleast 2 mols of a carboxylic acid amide of the formula:

r 2R-C O-NH (III) wherein R and R represent, independently of eachother, hydrogen or an alkyl radical, a cycloalkyl radical, an arylradical, optionally substituted by one or more alkyl groups, or anaralkyl radical,

with at least one mol of sulphur dichloride in the presence of an acidbinding agent.

The reaction of a compound of the Formula IH with sulphur dichloride maybe represented by the following reaction scheme:

The reaction is carried out at a temperature of from 50 C. to +50 0,preferably at C. to +10 C.

The quantities of the reactants used may vary within wide limits. If aliquid carboxylic acid amide of the Formula III enters into the reactionit may be advisable to use this component in excess, the carboxylic acidamide used then serving also as solvent. In general, however, thereactants are used in equimolecular quantities. If desired, an inertorganic solvent or diluent may, of course, be used as the reactionmedium. The following are examples of suitable solvents or diluents:hydrocarbons such as light fraction petroleum hydrocarbons, cleaningpetrol, hexane, cyclohexane, benzene toluene and Xylene; chlorinatedhydrocarbons such as methylene chloride, ethylene chloride, chloroform,carbon tetrachloride and chlorobenzene; ethers such as diethyl ether,diisopropyl ether dioxane and tetrahydrofuran; ketones such as acetone,methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl butylketone di-n-propyl ketone, methylisopropyl ketone and cyclohexanol.

Both inorganic and organic bases are suitable for use as the acidbinding agent. As a rule the acid binding agent used is a tertiary aminesuch as triethylamine, N,N- dimethyl aniline and especially a pyridinebase such as pyridine, an alkyl pyridine or quinoline, but an inorganicbase such as magnesium oxide, sodium carbonate, potassium carbonate orcalcium carbonate may also be used as the acid binding agent in whichcase, it may be advantageous to add these compounds in a finely dividedform. If the acid binding agent is a liquid compound, e.g. pyridine, itmay, of course, also serve as a solvent or diluent.

The reactants may be added in any sequence. As a rule carboxylic acidamide and the acid binding agent are introduced into the reaction vesseland sulphur dichloride, optionally dissolved in a solvent, is addedthereto. The products are worked up in the usual manner, e.g. by removalof the resulting aminohydrochloride or inorganic chloride (if aninorganic base was used as the acid bindiug agent) by filtration orwashing with water, followed by isolation of theN,N'-thio-bis-carboxylic acid amide. The new compounds are generallycolourless, crystalline substances.

The following are examples of acid amides (III) which may be used forthe reaction:

formamide,

acetamide,

propionamide,

N-methyl formamide,

N-methyl acetamide,

N-ethyl acetamide,

N-propyl acetamide,

N-methyl propionamide,

N-ethyl propionamide,

N-methyl butyric acid amide, N-ethyl butyric acid amide, N-methylisobutyric acid amide, N-ethyl isobutyric acid amide, N-methyl pentanecarboxylic acid amide, N-cyclohexylmethyl acetamide, N-cyclopentylacetamide, N-cyclohexyl acetamide, N-methylcyclohexyl acetamide,N-benzyl acetamide,

Nbenzyl formamide, N-phenyl-ethyl acetamide, N-phenyl formamide,

N-phenyl acetamide,

N-a-naphthyl acetamide. N-4-methylphenyl acetamide, N-4-ethylphenylacetamide, N-Z-methylphenyl acetamide, N-Z-ethylphenyl acetamide,N-2,3-dimethylphenyl acetamide, N-2,4-dimethyl phenyl acetamide,N-2,6-dimethylphenyl acetamide, N-2,5-diethylphenyl acetamide,N-3,4-diethylphenyl acetamide, N-2-methyl-4-ethylphenyl acetamide,N-4-methyl-3-ethylphenyl acetamide, N-2,3,4-trimethylphenyl acetamide,N-2,4,6-trirnethylphenyl acetamide, N-phenyl propionamide,N-Z-methylphenyl propionamide, N-benzyl propionamide,

N-phenyl butyric acid amide, benzamide,

N-methyl benzamide,

N-ethyl benzamide,

N-propyl benzamide, N-cyclohexyl benzamide, N-cyclopentyl benzamide,N-methylcyclohexyl benzamide, N-phenyl cyelohexane carboxylic acidamide,

N-4-methylphenylcyclohexane carboxylic acid amide, N-phenyl benzamide,

N-4-methylphenyl benzamide,

N-Z-methylphenyl benzamide,

N-3-methylphenyl benzamide,

N-phenyl-4-methyl benzamide, N-2-methylphenylmethyl benzamide,N-phenyl-2,4,6-trimethylbenzamide, N-methyl-2,4,6-trimethyl benzarnide,N-2-methylphenyl-2,4,6-trimethyl benzamide, N-2,6-dimethylphenylbenzamide, N-2,4,6-trimethylphenyl benzamide,

N-a-naphthyl benzamide,

N-,B-naphthyl benzamide,

N-phenyl-u-naphthalene carboxylic acid amide, N-a-naphthyl-a-naphthalenecarboxylic acid amide and N-phenyl-u-naphthalene carboxylic acid amide.

The following example illustrate the invention. The values shown in thetables are parts by weight, based on 100.0 parts by weight of therubber.

The test methods are defined as follows (see also Kautschuk und Gummi;Kunststoffe 20, No. 3/1967, pages 126-134, in particular pages 127 and133):

Complete vulcanisation time: Time taken to reach 90% of the maximumtension (at 300% elongation) at 140 C.

EXAMPLE 1.THE FOLLOWING MIXTURES WERE PREPARED ON ll/IIXING ROLLERSMixture number 1 2 3 Natural rubber, smoked sheets Zinc oxide Stearleacid Aromatic mineral oil plastieiser. High abrasion furnace blackNaphthenie mineral oil plasticiser cn wen OGIOQO SulphurN-cyclohexyl-2-benzothiazyl sulphenamide N-nitrosodiphenylemine (forcompariso NNEthio-bis-(N-phenyl aceta- O 2 m1N,N-bis-pyrrolidon-(2)-sulphide O. 3 N,N-bis-caprolactam sulphide or we:00100 us a\ we: omoo ca No'rE.The mixtures obtained were vulcanisedunder pressure to produce test samples 4 mm. in thickness, heating beingcarried out stepwise at 110 C. and 140 C. The results shown in Table Iwere obtained,-

10 of N-phenyl acetamide, 124.5 g. (1.575 mol) of pyridine and 750 ml.of methylene chloride. The reaction mixture is stirred for 3 hours andwashed thoroughly with water; the methylene chloride solution is driedover Na SO and concentrated by evaporation under vacuum. The residue isrecrystallised from isopropanol; M.P. 132 C. to 134 C.

When the amides listed under A in the following Table II are usedinstead of N-phenyl acetamide, the compounds shown under B are obtained.

TABLE II Melting point, A B C (3H (EH CliH 132-134 (i=0 (17:0 (1:0 NHNSN- (H) (3H, (I? CH (3H3 (I? -66 CHa-C-NH H3CC-NS-NCCHs 0 CH 0 CH CH 0II I II I CNH ONS -NC (f (I)l 134-136 II II It Will be seen that the newretarders added in a dose of 0.2 and 0.3% by weight, respectively, basedon 100.0 parts by weight of rubber, have the same retarding eifect asN-nitrosodiphenylamine added in an amount of 0.6% by weight. It follows,therefore, that the new retarders are at least twice as effective and insome cases even more so (see Table I I).

The time required for complete vulcanisation is invariably less in thecase of the compounds prepared according to the invention than in thecase of the mixture pre- TABLE I Complete Mechanical valuescorresponding to the Scorch vulcanisacomplete vulcanisation time timetion time Mixture at C. at 140 C. F (kg. D M 300 (kg. H number Scorchretarder (min.) (min.) wt.lem. (percent) wit/cm?) (Shore A) 1 None 63. 022. 5 240 550 105 61 2 N-nitroso-diphenylamine (for 84.5 28.3 220 560 9760 comparison). N,N'-thi0-bis-(N-phenylacetamide) 83.5 24.4 210 500 10862 N,N-th iobiS-(pyrr0lidone-2) 85.0 24. 9 230 510 112 62 5N,N-thio-bis-(caprolactam) 83. 0 24. 2 235 530 110 63 EXAMPLE 2 Asolution of 76.5 g. (0.75 mol) of sulphur dichloride in ml. of methylenechloride is introduced dropwise pared with N-nitrosodiphenylamine. Thisshows clearly the very advantageous influence of the compounds usedaccording to the invention on the vulcanisation characwith stirring at 0C. into a mixture of 202.5 g. (1.5 mol) 75 teristic.

1 1 What is claimed is: 1. A compound of the formula l x R'-0-Ns-1I-o-R' a 2;

wherein R and R are, independently of each other, alkyl having from 1 to6 carbon atoms, cyclohexylmethyl, cycloalkyl having from 5 to 6 carbonatoms, methylcyclohexyl phenylalkyl having from 1 to 3 carbon atoms inthe alkyl moiety, phenyl, -naphthyl, monoalkylphenyl having from 1 to 4carbon atoms in the alkyl moiety, dialkylphenyl having from 1 to 2carbon atoms in each alkyl moiety and trialkylphenyl having from 1 to 2carbon atoms in each alkyl moiety.

2. The compound of claim 1 wherein R is methyl and R is phenyl.

3. The compound of claim 1 wherein each of R and R is methyl.

4. The compound of claim 1 wherein R is phenyl and R is methyl.

References Cited Hope et al., J. Chem. Soc. (London), pp. 5679-83 HARRYI. MOATZ, Primary Examiner

